More fogging to fight dengue but experts question effectiveness

This article is more than 12 months old

As the battle with dengue continues, more building and premise owners are turning to fogging as part of control efforts.

In response to queries from The Straits Times, the National Environment Agency (NEA) said there was a 82 per cent rise in the number of fogging operations between May and June this year, compared with the two-month period from February.

The increase coincided with the start of the spike in dengue cases in the current outbreak, the agency added in a statement on Saturday.

There were 1,736 infections diagnosed last week and 18,673 people have been infected since January.


But while there is more fogging now, experts are not so clear if it actually helps.

Professor Ooi Eng Eong said there is "no solid and consistent evidence" that fogging works to bring the number of dengue cases down - even in areas where there are clusters.

The deputy director of the emerging infectious diseases programme at Duke-NUS Medical School added: "What is clear, however, is that if the number of Aedes mosquito breeding sites can be eliminated, the mosquito population and incidence of dengue cases will correspondingly shrink.

"We should all, thus, take steps to prevent Aedes breeding instead of placing hopes on mosquito fogging to reduce the risk of dengue."

Mr Declan Ee, director of local pest control company Ikari Services, said fogging kills only mosquitoes present at that time and the insects that prey on them.

"Most of the time, the mosquitoes simply move away to the neighbouring areas (when you do fogging)," said Mr Ee.

In its reply to ST, NEA said that fogging should be "used judiciously and not as a routine mosquito control measure".

"Fogging is not mandatory, but is recommended where there is an increased presence of adult mosquitoes, or necessitated by the need to eliminate infective mosquitoes immediately during a dengue or other mosquito-borne disease outbreak," the agency added.